1. Field of the Invention
The present invention relates to a suspension system which is interposed between a vehicle body and an axle, and has a coil spring.
2. Description of the Related Art
Conventionally, in an assembly state of a suspension system before being mounted to a vehicle, a coil spring is slightly compressed and is interposed between a lower spring seat mounted on a damper cylinder and an upper spring seat mounted on a piston rod. In the case of mounting the suspension system, which is in the aforesaid assembly state to the vehicle, a lower portion of the damper cylinder is connected to an axle side mounting portion, and then, the upper spring seat mounted on the piston rod is connected to a vehicle body side mounting portion.
However, the coil spring assembled into the suspension system usually causes a curvature of its belly due to eccentricity of a load to the center axis of the coil spring. The body warp of the coil spring is a factor of tilting the upper spring seat to the center axis of the suspension system. In order to mount the suspension system having a tilted upper spring seat, to the vehicle, the upper spring seat is flush with a surface of the vehicle body side mounting portion, and because of this, the lower portion of the damper cylinder greatly diverges from the axle side mounting portion; for this reason, it is very difficult to mount the suspension system to the vehicle.
In order to prevent body warp of the spring coil after the suspension system is mounted to the vehicle (not assembly state before being connected to the vehicle), there has been proposed the invention shown in Japanese Patent Application Publication (JP-B) No. 63-25217, as prior art. This Publication discloses the technique of fitting a tilted-surface annular spacer into the spring seat in a direction to compress a convex portion side of the body warp of the coil spring. The aforesaid prior art is applied to the suspension system which is in an assembly state before being connected to the vehicle. However, in the prior art, a tilted surface is provided on the overall circumferential direction of the spring seat so that the entire circumferential portion of the coil spring is in contact with the tilted surface. As a result, a compressive force is applied to the coil spring over the circumferential portion of the coil spring. For this reason, a compressive force is applied to the convex portion side of the body warp of the coil spring to some degree. This creates the possibility of producing a body warp in the coil spring, and consequently, the body warp of the coil spring is not prevented. Further, in the prior art, the annular spacer is fitted into the spring seat; for this reason, the number of components is increased, and also, assembly is more difficult.